However, in models with extended Higgs sectors such as the NMSSM, heavy scalars can have sizeable branching fractions into two lighter scalars, or a \(Z\)  boson and one scalar. For scalars with small direct production cross sections, such processes can be the only way to discover them. Corresponding searches have been performed in [1]}, [2]}, [3]}, [4]}, [5]}, [6]}, [7]}, [8]}.
Finally heavy CP-even scalars can also be searched for in final states corresponding to resonant SM Higgs pair production, see
[9]}, [10]}, [11]}, [12]}, [13]}, [14]}, [15]}, [16]}, [17]}, [18]}.
For a recent review of boson pair production at the LHC see [19]}.
